Method for removing an ultraviolet light cured floor finish, removable ultraviolet light curable floor finish and strippable finished floor

ABSTRACT

A UV cured floor finish can be removed from a floor by applying to the cured finish an inhomogeneous stripper composition containing at least one polar solvent, allowing the stripper composition to contact the finish for sufficient time to soften the finish, and removing the softened finish from the floor by mopping, vacuuming, mild abrasion or other measures that do not remove substantial portions of the floor. Preferably the polar solvent is denser than water and preferably the stripper composition has a diffusion rate through the cured finish greater than about 7×10 −7  g/cm 2 /sec. Strippable-floor finish kits can be manufactured by combining a UV curable floor finish composition and an inhomogeneous stripper composition containing at least one polar solvent.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of the filing date of copending U.S.Provisional Application Ser. No. 60/150,655, filed Aug. 25, 1999, andcopending U.S. patent application Ser. Nos. 09/383,000 filed Aug. 25,1999, and Ser. 09/560,170 filed Apr. 28, 2000.

TECHNICAL FIELD

This invention relates to a method for removing a floor finish, to aremovable floor finish and stripper, and to a floor coated with such afinish and stripper.

BACKGROUND

Ultraviolet (“UV”) light curable coating compositions typically providea desirable combination of properties including rapid cure, high glossand good durability. Due to these properties and their generally goodscratch and detergent resistance, UV light curable coating compositionshave been used as floor finishes. Eventually, even a UV light curedfloor finish will show the effects of wear, and will require removal andrenewal. UV cured floor finishes generally are not regarded as beingremovable using conventional chemical floor stripping agents. Instead,more aggressive removal techniques such as floor sanding typically mustbe employed. This can cause potential dust problems in the workplace andcan remove a portion of the underlying floor surface. This hasdiscouraged the use of UV cured floor finishes, particularly on vinyltile, vinyl sheeting and other resilient flooring materials.

SUMMARY OF THE INVENTION

The present invention provides, in one aspect, a method for removing aUV cured floor finish from a floor, comprising the steps of applying tothe cured finish an inhomogeneous stripper composition containing atleast one polar solvent, allowing the stripper composition to contactthe finish for sufficient time to soften the finish, and removing thesoftened finish from the floor by mopping, vacuuming, mild abrasion orother measures that do not remove substantial portions of the floor. Ina preferred embodiment, the polar solvent is denser than water. In afurther preferred embodiment, the stripper composition has a diffusionrate through the cured finish greater than about 7×10⁻⁷ g/²/sec.

In another aspect, the invention provides a strippable floor finish kitcomprising a UV curable floor finish composition and an inhomogeneousstripper composition containing at least one polar solvent.

In a further aspect, the invention provides a floor coated with a UVcured floor finish covered with an inhomogeneous stripper compositioncontaining at least one polar solvent, wherein the stripper compositionsoftens the floor finish and permits removal thereof.

DETAILED DESCRIPTION

A variety of flooring materials can be coated with an ultraviolet curedfloor finish and later stripped according to the invention to remove thefinish, including wood floors, resilient floors, concrete floors,synthetic sports floors, and combinations thereof. The invention isparticularly well suited for use in high traffic areas such as hallways,stairs, kitchens and meeting rooms, where a wear-resistant but renewablefinish will be desired.

A variety of UV curable floor finish compositions can be used in theinvention. Preferred UV curable floor finish compositions includeemulsion compositions and 100% solids compositions. The emulsioncompositions generally include a flowable mixture of polymer formingcomponents and water, and the 100% solids compositions generally includea flowable mixture of polymer forming components in the substantialabsence of water. The polymer forming components react to form acontinuous or substantially continuous polymeric film on the floorsurface. In general, the polymer forming components include reactivepolymers, oligomers, or monomers or mixtures thereof. The UV curablefloor finish composition typically also contains an ultravioletlight-activated photoinitiator in an amount sufficient to permit curingof the polymer forming components upon exposure to ultraviolet light,and optionally one or more additives that enhance the applicationcharacteristics, performance or removal characteristics of the floorfinish.

Useful classes of UV curable polymer forming components includemonoacrylates, diacrylates, triacrylates, polyacrylates, polyurethanes,polyurethane acrylates (e.g., aliphatic polyurethane acrylates),polyester acrylates (e.g., polyester diacrylates), vinyl acrylates,epoxy acrylates, ethoxylated bisphenol A diacrylates, trifunctionalacrylic esters, unsaturated cyclic diones, and mixtures or copolymersthereof. Waterborne acrylates and urethanes are particularly preferred.Representative polymer forming components include, but are not limitedto, trimethylolpropane triacrylate, alkoxylated trimethylolpropanetriacrylate (e.g., ethoxylated or propoxylated trimethylolpropanetriacrylate), 1,6-hexane diol diacrylate, isobornyl acrylate, andmixtures thereof. Suitable commercially or experimentally availablepolymer forming components include UV curable acrylates, urethanes andurethane acrylates (including aliphatic polyester urethane acrylates)such as the materials designated as 935-63 through 935-67; 935-75B;935-76 and 935-80 through 935-82 series of coatings from UV CoatingsLimited; the materials described in U.S. Pat. Nos. 5,453,451 and5,773,487; RoShield™ 3120 UV curable acrylate coating from Rohm & Haas;NeoRad™ NR-3709 UV curable aliphatic urethane coating from ZenecaResins; Laromer™ PE 55W polyester acrylate, LR 8895 polyester acrylate,LR 8949 aliphatic urethane and LR 8983 aromatic urethane waterborneacrylic ester resins, all available from BASF Corp.; Viaktin™ VTE 6155aliphatic urethane acrylate, VTE 6165 aromatic urethane acrylate and VTE6169 aliphatic polyester urethane radiation curing resins, all availablefrom Vianova Resins GmbH & Co. KG; 98-283W urethane acrylate, availablefrom Hans Rahn & Co.; and the materials described in U.S. Pat. No5,830,937.

Exemplary photoinitiators which can be used in the UV curable floorfinish composition include, but are not limited to,1-phenyl-2-hydroxy-2-methyl-1-propanone; oligo{2-hydroxy-2methyl-1-[4-(methylvinyl)phenyl]propanone}; 2-hydroxy 2-methyl 1-phenylpropan-1 one; bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentyl phosphineoxide; 2,4,6-trimethyl benzoyl-diphenyl phosphine oxide;2-methyl-1-[4(methylthio)-2-morpholinopropan]-1-one; 1-hydroxycyclohexylphenyl ketone; 4-(2-hydroxy) phenyl-2-hydroxy-2-(methylpropyl)ketone;2,2-dimethoxy-2-phenyl acetophenone; benzophenone; benzoic acid;(n-5,2,4-cyclopentadien-1-yl)[1,2,3,4,5,6-n)-(1-methylethyl)benzene]-iron(+)hexafluorophosphate; 4-(dimethyl amino)-ethyl ether; and mixturesthereof. Commercially available photoinitiators include1-hydroxycyclohexylphenylketone (IRGACURE™ 184, commercially availablefrom Ciba Specialty Chemicals); a 50:50 weight basis mixture of1-hydroxycyclohexylphenylketone and benzophenone (IRGACURE™ 500,commercially available from Ciba Specialty Chemicals);bis(n,5,2,4-cyclopentadien-1-yl)-bis[2,6-difluoro-3-(1H-pyrol-1-yl)phenyl]titanium(IRGACURE™ 784 DC, commercially available from Ciba SpecialtyChemicals); 2-benzyl-2-N,N-dimethylamino-1-(4-morpholinophenyl)-1-butanone (IRGACURE™ 369, commerciallyavailable from Ciba Specialty Chemicals); and the EB3, KB1, TZT, KIP100F, ITX, EDB, X15 and KT37 series of ESACURE™ photoinitiators(commercially available from Sartomer Inc.).

The UV curable finish composition can contain a variety of adjuvants toalter its performance or other properties before or after application toflooring. Useful adjuvants include leveling agents and othersurface-active agents, defoamers, solvents to accelerate or to slow thedrying rate, waxes, fillers, indicators and colorants. The types andamounts of such adjuvants will be apparent to those skilled in the art.

The UV curable floor finish composition preferably contains about 50 wt.% to about 99.9 wt. % polymer forming components and about 0.1 wt. % toabout 15 wt. % photoinitiator, based on the total weight of solids inthe composition. More preferably, the composition contains about 93 wt.% to about 99.9 wt. % polymer forming components and about 0.1 wt. % toabout 7 wt. % photoinitiator based on the total weight of solids.

One useful subclass of UV curable floor finish compositions for use inthe invention contains one or more UV curable polymer formingcomponents, one or more alkali soluble resins, and a suitablephotoinitiator. The UV curable polymer forming component preferably is apolyacrylate polymer or polyurethane polymer. The alkali soluble resinpreferably has a low number average molecular weight (e.g., less thanabout 50,000, and more preferably less than about 30,000). Suitablealkali soluble resins include polycarboxylic acid homopolymers,copolymers (e.g., styrene-maleic anhydride copolymers) and mixturesthereof, and rosin esters. The amount of alkali soluble resin in suchcompositions preferably is between about 1 wt. % and about 30 wt. % andmore preferably between about 2 wt. % and about 15 wt. %.

Another useful subclass of UV curable floor finish compositions for usein the invention contains two or more acrylate polymer formingcomponents of different molecular weights present in amounts sufficientso that the uncured composition has a viscosity between about 2centipoise and about 1,500 centipoise at about 25° C.

Preferred stripper compositions for use in the invention areinhomogeneous, that is, they do not form a transparent, haze-freesingle-phase solution when mixed at the intended use dilution with anydesired diluents (e.g., water). For the purposes of this invention, astripper composition that forms a hazy or cloudy single-phase solutionwhen so prepared and freshly stirred, or that separates into two phaseswhen so prepared and allowed to stand, will be regarded asinhomogeneous. The stripper composition contains a polar solvent.Preferably the polar solvent is denser than water. Suitable dense polarsolvents include acetamidophenol (specific gravity 1.027); acetanilide(specific gravity 1.219); acetophenone (specific gravity 1.0238);2-acetyl-1-methylpyrrole (specific gravity 1.04); benzyl acetate(specific gravity 1.0515); benzyl alcohol (specific gravity 1.0413);benzyl benzoate (specific gravity 1.118); benzyloxyethanol (specificgravity 1.07); ethylene glycol phenyl ether (specific gravity 1.104;commercially available as DOWANOL EPH™ from Dow Chemical Co.); andpropylene glycol phenyl ether (specific gravity 1.063; commerciallyavailable as DOWANOL PPH™ from Dow Chemical Co.). Benzyl alcohol,ethylene glycol phenyl ether and propylene glycol phenyl ether areparticularly preferred dense polar solvents. Less dense polar solventsthat can be used alone or in combination with one or more other polarsolvents include 2-(2-aminoethoxy)ethanol, amyl acetate, amyl alcohol,butanol, 3-butoxyethyl-2-propanol, butyl acetate, n-butyl propionate,cyclohexanone, diacetone alcohol, diethoxyethanol, diethylene glycolmethyl ether, diethylene glycol n-butyl ether, diisobutyl carbinol,diisobutyl ketone, dimethyl heptanol, dipropylene glycol n-butyl ether,dipropylene glycol methyl ether, dipropylene glycol propyl ether,dipropylene glycol tert-butyl ether, ethanol, ethyl acetate,2-ethylhexanol, ethyl propionate, ethylene glycol butyl ether, ethyleneglycol methyl ether acetate, hexanol, isobutanol, isobutyl acetate,isobutyl heptyl ketone, isophorone, isopropanol, isopropyl acetate,methanol, methyl amyl alcohol, methyl n-amyl ketone, 2-methyl-1-butanol,methyl ethyl ketone, methyl isobutyl ketone, 1-pentanol, n-pentylpropionate, 1-propanol, n-propyl acetate,n-propyl propionate, propyleneglycol n-butyl ether, propylene glycol ethyl ether, propylene glycolmethyl ether, propylene glycol n-propyl ether, tripropylene glycolmethyl ether and tripropylene glycol n-butyl ether. Commerciallyavailable less dense polar solvents (all of which are available fromUnion Carbide Corp.) include Butoxyethyl PROPASOL™, Butyl CARBITOL™acetate, Butyl CARBITOL™, Butyl CELLOSOLVE™ acetate, Butyl CELLOSOLVE™,Butyl DIPROPASOL™, Butyl PROPASOL™, CARBITOL™ PM-600, CARBITOL™ LowGravity, CELLOSOLVE™ acetate, CELLOSOLVE™, Ester EEP™, Filmer IB™, HexylCARBITOL™, Hexyl CELLOSOLVE™, Methyl CARBITOL™, MethylCELLOSOLVE™acetate, Methyl CELLOSOLVE™, Methyl DIPROPASOL™, MethylPROPASOL™ acetate, Methyl PROPASOL™, Propyl CARBITOL™, PropylCELLOSOLVE™, Propyl DIPROPASOL™ and Propyl PROPASOL™.

In a preferred embodiment, the stripper composition has a diffusion ratethrough the cured finish greater than about 7×10⁻⁷ g/cm²/sec, morepreferably greater than about 1×10⁻⁶ g/cm²/sec. This diffusion rate willdepend on both the choice of cured finish and stripper, and can beevaluated using the Diffusion Rate Test Method set out below.

One useful subclass of stripper compositions for use in the inventioncontains about 10 wt. % to about 40 wt. % water-soluble glycol ether,about 1 wt. % to about 40 wt. % alkali or alkanolamine, about 1 wt. % toabout 20 wt. % surfactant, and up to about 5 wt. % adjuvants (e.g.,thickeners). Similar stripper compositions have been used insubstantially diluted form (e.g., at stripper composition:water ratiosof about 10:1 to 5:1) to remove conventional (non-UV cured) floorfinishes. Suitable stripper compositions that have been so used includeHawk™ and Care Strip Low Odor™ stripper concentrates (commerciallyavailable from Ecolab, Inc.). For removal of UV cured floor finishes,these commercially available stripper compositions are preferably usedby diluting them with water at a lower dilution rate (in other words, ata higher concentration of active ingredients) and by employing longerstanding times than are recommended for use on conventional floorfinishes.

Another useful subclass of stripper compositions for use in theinvention contains a blend of primary solvent and one or more etheralcohol solvent couplers in the substantial absence of water. Suchcompositions form concentrates that can be used alone or combined withwater to form a dispersion or emulsion. Preferred stripper compositionsin this subclass contain a blend of primary solvent, firstsolvent/coupler and second solvent/coupler that together form theorganic phase of a dispersion when combined with water. In suchpreferred stripper compositions, the water solubility of the firstsolvent/coupler is greater than the water solubility of the secondsolvent coupler and the water solubility of the second solvent/coupleris greater than the water solubility of the primary solvent. Forexample, the blend can contain about 1 to about 75 wt. % of a firstether alcohol solvent having a solubility in water of less than about 5wt. % of the solvent, and about 1 to about 75 wt. % of a second etheralcohol solvent/coupler having a solubility in water of about 20 toabout 100 wt. % of the solvent coupler, and wherein the vapor pressureof the blend is less than 1 mm-Hg. More preferably, the primary solventhas a water solubility less than about 3 wt. %, the secondsolvent/coupler has a water solubility of about 1 wt. % to about 30 wt.%, and the first solvent coupler has a water solubility of about 50 wt.% to about 100 wt.%. Most preferably, the primary solvent has a watersolubility less than about 2 wt. %, the second solvent/coupler has awater solubility of about 1 wt. % to about 15 wt. %, and the firstsolvent coupler has a water solubility of about 80 wt. % to about 100wt.%. Preferably the overall combined amount of primary solvent andsolvent/coupler materials exceeds the water solubility of the organicphase. This promotes formation of an inhomogeneous dispersion that isvisibly hazy, cloudy or opaque. Preferred primary solvents in suchcompositions are phenyl ethers (e.g., an ethylene glycol or propyleneglycol phenyl ether) and the preferred solvent/couplers are alkyleneglycol alkyl ethers (e.g., an ethylene glycol or propylene glycol butylether). Stripper compositions of this subclass are described in moredetail in copending U.S. patent application Ser. No. 09/383,000 filedAug. 25, 1999, the disclosure of which is incorporated by reference.

Another useful subclass of stripper compositions for use in theinvention involves concentrates containing a polar solvent that isdenser than water, and a sufficiently low level of cosolvent orsurfactant so that upon mixing with water a pseudo-stable aqueousdispersion forms which will phase-separate following application to asurface. Such concentrates are described in greater detail in co-pendingapplication Serial No. (Attorney Docket No. 103-1361.00), filed on evendate herewith, the disclosure of which is incorporated herein byreference. This subclass of stripper compositions is particularlypreferred for use in the present invention.

Although no longer commercially available, an aqueous stripping agentconcentrate previously sold in Canada as Fuller Formula 3100™ SuperConcentrate (Fuller Brush, Québec) could be used in the presentinvention, if employed at a dilution ratio not recommended in theproduct instructions. Fuller Formula 3100™ Super Concentrate is believedto have contained about 49% benzyl alcohol, 17% monoethanolamine, 10%sodium decyldiphenyl ether disulfonate and 24% water. Dilution of theconcentrate at a 1:20 concentrate:water ratio was recommended on theproduct instructions. At that dilution ratio, the resulting mixtureformed a stable single-phase solution. However, if diluted at asufficiently larger concentrate:water ratio (e.g., 1: 10), the resultingmixture forms a pseudo-stable dispersion that will undergo phasesplitting when applied to a substrate and allowed to stand for a fewminutes. A product known as Twist and Fill™ stripper concentrate from 3Mcan also be employed in the present invention. It preferably is used ata concentrate:water dilution ratio of about 1:10 or more (e.g., 1:5).

The stripper composition can contain a variety of adjuvants to alter itsperformance or other properties before or after application to flooring.Useful adjuvants include defoamers, solvents, indicators and colorants.Although surfactants can also be added to the stripper composition, ingeneral the use of excessive amounts of surfactants is not preferred, asthey tend to make the composition form a homogeneous rather than aninhomogeneous composition. With this precaution in mind, the types andamounts of surfactants and other adjuvants will be apparent to thoseskilled in the art.

The UV curable floor finish composition can be applied to a floor usinga variety of methods, including spraying, brushing, roll coating andflood coating. Mop or sponge application is preferred for coating vinylcomposite tile floors. Typically the substrate should first be cleanedand any loose debris removed. The composition should be applied andallowed to level. In the case of compositions in the form of aqueousemulsions or dispersions, the applied composition preferably will becomesubstantially free of carrier liquid (e.g., water or solvent) withinabout 30 minutes after application. Such compositions do not have tobecome dry to the touch prior to curing, but instead can be cured whilein a tacky or moist state. In the case of 100% solids compositions, theapplied composition preferably will remain fluid until cured byultraviolet light radiation. For applied compositions in the form ofemulsions, dispersions or 100% solids compositions, curing can becarried out using stationary, portable or mobile UV curing equipment,with mobile equipment generally being preferred. Suitable equipment isdescribed, for example, in Japanese Published Patent Application (Kokai)No. 6-134381. Sufficient ultraviolet light of a suitable spectral rangeshould be applied to provide the desired degree cross-linking densityand generate a hard, cured floor finish in a suitably brief period oftime.

Usually two or more coats (more preferably, three to six coats) of thefloor finish composition are diluted if necessary with water or anothersuitable solvent, applied and cured. If desired, different UV floorfinish compositions can be employed in the various coats in order tooptimize properties such as adhesion to the flooring substrate, floorfinish surface appearance or properties, wear resistance, strippability,and other desired properties.

In any event, each coat preferably will have a cured coating thicknessof about 2.5 to about 75 micrometers, more preferably about 2.5 to about20 micrometers, and the overall floor finish cured coating thicknesspreferably will be about 5.0 to about 450 micrometers, more preferablyabout 15 to about 120 micrometers.

The cured finish composition can thereafter receive normal maintenanceuntil such time as it is desired to remove and renew the finish. Thefinish can be stripped by optionally abrading it with a suitably mildabrasive (e.g., a green or black Scotch-Brite™ Floor Maintenance pad, ora High Productivity Pad, these being commercially available from 3M) andthen applying one or more coats of the stripper composition in an amountsufficient to wet the finish. Preferably the stripper composition isapplied the floor finish by mopping. The stripper should be allowed tostand for a suitable time (e.g., for a minute or more, and typicallybetween about 5 and about 40 minutes) while it diffuses through andsoftens the floor finish. Some UV-cured floor finishes will requirestripper standing times of 20 to 30 minutes or more in order for thestripper to diffuse sufficiently into and sufficiently soften thefinish. Preferably the stripper composition is not allowed to completelyevaporate from the floor finish. After the finish softens sufficiently,it can be removed using a variety of techniques. Removal will be madeeasier by employing a conventional rotating pad floor machine orportable automatic scrubbing machine. Suitable rotating pads arecommercially available from several sources including Glit MicrotronAbrasives Inc. and 3M. Removal will also be made easier if water or asuitable detergent solution is applied to the softened finish. In anyevent, the softened floor finish can be removed from the floor viamopping, vacuuming (e.g., wet vacuuming), wiping or other knowntechniques. The floor can be allowed to dry and new layers of the UVcurable floor finish composition can be applied and cured to renew thefinish.

The compositions of the invention can be sold in the form of a kitcontaining the UV curable floor finish composition and strippercomposition in containers (e.g., separate containers) together withsuitable directions for carrying out the methods of the invention. Ifdesired, the UV curable floor finish composition can be packaged as aconcentrate intended to be mixed with water or another suitable solventat about a 15-40% solids level prior to use. The stripper compositionusually will be packaged as a concentrate intended to be mixed withwater or another suitable solvent at about 5-30% by weight prior to use.The kit can also contain undercoat materials (e.g., leveling coatings)that can be applied to the floor before application of the UV curablefloor finish composition, and overcoat materials (e.g., wax finishes)that can be applied atop the finish.

The invention is further illustrated in the following non-limitingexamples, in which all parts and percentages are by weight unlessotherwise indicated. The following formulations and procedures wereemployed in the examples:

UV Curable Finish Compositions

Two waterborne UV curable coating formulations were prepared from theingredients set out below in Table 1:

TABLE 1 Ingredient Finish A, Parts Finish B, Parts Viaktin ™ VTE 6165resin¹ 42.86 Viaktin ™ VTE 6169 resin² 42.86 Irgacure 500photoinitiator³ 1.57 1.57 Wax 325 polymer emulsion⁴ 1.05 0.53 Wax 43Npolymer emulsion⁵ 1.05 1.58 PI-35 defoamer⁵, 10% 0.1 0.1 solution inwater FC-120 fluorosurfactant⁶, 0.05 0.05 10% solution in waterDeionized water 53.32 53.32 ¹Aromatic urethane acrylate radiation curingresin, available from Vianova Resins GmbH & Co. KG ²Aliphatic polyesterurethane radiation curing resins, available from Vianova Resins GmbH &Co. KG ³Available from Ciba Specialty Chemicals ⁴Available from EmulsionSystems, Inc. ⁵Available from Ultra Additives, Inc. ⁶Available from 3M

Diluted Stripper Compositions

Aqueous solutions of the following stripper compositions were dilutedwith deionized water as shown:

Stripper B1: Concentrate¹ at 1:9 dilution (10% in water)

Stripper B2: Concentrate¹ at 1:4 dilution (20% in water)

Stripper E1: Concentrate² at 1:9 dilution (10% in water)

Stripper E2: Concentrate² at 1:4 dilution (20% in water)

Stripper F1: Concentrate³ at 1:9 dilution (10% in water)

Stripper F2: Concentrate³ at 1:4 dilution (20% in water)

¹ Juggernaut™ stripper concentrate from Buckeye International, Inc.

² Concentrate containing 59% softened water, 6% sodium xylene sulfonate,4.5% potassium hydroxide, 10% monoethanolamine, 0.2% tetrasodium EDTA,10% ethylene glycol phenyl ether and 0.05% fluorosurfactant (FC-129,3M).

³ Concentrate containing 49% benzyl alcohol, 17% monoethanolamine, 24%water and 10% sodium decyldiphenyl ether disulfonate.

Substrate Coating Procedure

Black 150 mm square vinyl composite floor tiles from Armstrong Tile orfrom American Biltrite Limited were coated with 4 coats or 6 coats ofvarious UV curable finishes applied at a 20% solids level (equivalent toa coverage rate of 1.9 gm per coat). Each coat was allowed to air drybefore application of the next coat. A control set of tiles was coatedwith 4 coats or 6 coats of a waterborne metal-catalyzed acrylic floorfinish (Gemstar Laser™, Ecolab Inc.), with each coat being allowed toair dry before application of the next coat. Both the UV curable andcontrol tiles were passed through a UV curing apparatus containing an Hbulb mercury vapor lamp operated at 1.9 joule/sec per cm² and 4.9 metersper minute. The cured tiles were allowed to stand for at least 7 days,cut into 51mm×51mm square pieces and weighed on an analytical balance.

Diffusion Rate Test Method

A rubber O-ring having an inside diameter of about 32 mm and a thicknessof about 3 mm was exposed to each of the Diluted Stripper Compositionsshown above to verify that the O-ring would not be attacked by theDiluted Stripper Compositions. The O-ring was then placed in the middleof one of the coated tile square pieces and covered with a 50 mmdiameter by 38 mm high carbon steel cylinder having a weight of 571grams. A 6 mm central circular hole had been drilled through the centralaxis of the cylinder. The hole in the cylinder was centered above theO-ring. Samples of various stripper compositions were mixed with waterto form dispersions or solutions containing 20% active ingredients.Using two runs, a 2 g portion of the tested dilute stripper compositionwas placed in the hole and allowed to contact the coated finish for 20or 30 minutes. The cylinder was then removed from the tile, excessstripper was blotted away and the tile was re-weighed to determine theamount of the stripper composition that had diffused into the finish.The results were recorded in gm/cm²/sec.

Strippability Evaluation Method

The coated tile pieces were exposed to various stripper compositions andevaluated to determine the ease or difficulty of finish removal. Theabove-mentioned 50 mm diameter by 38 mm high carbon steel cylinder waswrapped with a green nonwoven pad (Scotch-Brite™ Floor Maintenance Disc,3M). When rolled over a coated tile, the cylinder exerted a pressure of2.8 kPa and mimicked the pressure applied by a standard electric floorburnisher. The coated tiles were placed on a level surface and floodedwith a sufficient quantity of 10% or 20% aqueous solutions of variousstripper compositions to form a 50 mm diameter circular pool on thesurface of the coated tiles. The stripper compositions were allowed toremain on the coated tiles for 10, 20 or 30 minute standing times. Thecylinder was then rolled 10 times over each tile. The tiles were rinsedwith tap water, blotted dry and rated according to the following scale:

1) No effect

2) Minimal chemical attack on coating

3) Moderate chemical attack on coating

4) Severe chemical attack on coating with onset of stripping

5) Incomplete strip (may strip completely in some areas, especiallywhere coating was porous, but not in other areas. Finish is slightlysoft or tacky)

6) Partial strip with softened finish in all areas

7) Complete strip.

Ratings of 3 or greater were regarded as indicating that the coatingcould be stripped using the selected stripper composition.

EXAMPLE I

Using the Substrate Coating Procedure, Diffusion Rate Test Method andStrippability Evaluation Method set out above, various Diluted StripperCompositions were applied to 4 tile pieces coated with UV curable FinishA, allowed to stand for 10 minutes and evaluated to determine thediffusion rate of the Diluted Stripper Composition through the UVcurable finish composition and the ease or difficulty of finish removal.The results are set out below in Table 2. Stripper Composition F2 wasinhomogeneous and the remaining Stripper Compositions were homogeneous.

TABLE 2 Stripper Diffusion Rate, gm/cm²/sec Strippability EvaluationFinish A Strippability Diffusion Rate 4 Coats Finish A 6 Coats Finish AStripper 4 Coats 6 Coats 10 Min. 20 Min. 10 Min. 20 Min. B1 — — 1 1 1 1B2 3.1E−07 5.3E−07 1 1 1 1 E1 — — 1 2 1 2 E2 2.3E−07 2.9E−07 1 2 1 2 F1— — 4 4 4 4 F2 9.1E−07 8.6E−07 4 4 4 3

COMPARISON EXAMPLE

Using the method of Example 1, the Diluted Stripper Compositions set outabove were applied to the control tiles (tiles coated with GemstarLaser™ waterborne metal-catalyzed acrylic floor finish). and evaluatedto determine the ease or difficulty of finish removal. The control tilesexhibited a strippability rating of 7 when exposed to the DilutedStripper Compositions. However, the control finish also exhibitssubstantially less durability and scratch resistance than the UV curablefinish of Example 1.

EXAMPLE 2

Using the method of Example 1, but using 10, 20, and 30 minute standingtimes, the Diluted Stripper Compositions used in Example 1 were appliedto tiles coated with UV curable Finish B and evaluated to determine thediffusion rate of the Diluted Stripper Composition through the UVcurable finish composition and the ease or difficulty of finish removal.The results are set out below in Table 3.

TABLE 3 Stripper Diffusion Rate, gm/cm²/sec Strippability EvaluationFinish B Strippability Diffusion Rate 4 Coats Finish B 6 Coats Finish BStripper 4 Coats 6 Coats 10 Min. 20 Min. 10 Min. 20 Min. 30 Min. B1 — —2 2 2 2 — B2 7.0E-07 3.7E-07 2 2 2 2 2 E1 — — 2 2 2 2 — E2 3.3E-074.4E-07 2 2 2 2 2 F1 — — 2 2 2 2 — F2 1.7E-06 1.9E-06 2 7 2 2 6

Finish B was more difficult to strip than Finish A, especially when morecoats had been applied to the tiles. However, by using longer standingtimes, satisfactory strippability ratings could be obtained usingStripper F2.

A plot of the observed Strip Agent diffusion rates and strippabilityratings for Examples 1 and 2 showed a good correlation between diffusionrate and strippability rating. In general, diffusion rates above about7×10⁷ gm/cm²/sec yielded strippability ratings of 3 or more, providedthat a sufficiently long standing time was employed.

Various modifications and alterations of this invention will be apparentto those skilled in the art without departing from the scope and spiritof this invention. It should be understood that this invention is notlimited to the illustrative embodiments set forth above.

We claim:
 1. A strippable floor finish kit comprising a UV curable floorfinish composition and an inhomogeneous stripper composition containingat least one polar solvent.
 2. A kit according to claim 1, wherein thefloor finish composition is an emulsion comprising a flowable mixture ofpolymer forming components and water.
 3. A kit according to claim 2,wherein the floor finish composition includes a polymer formingcomponent selected from the group consisting of waterborne acrylates,urethanes and urethane acrylates.
 4. A kit according to claim 1, whereinthe floor finish composition comprises one or more UV curable polymerforming components, one or more alkali soluble resins, and aphotoinitiator.
 5. A kit according to claim 4, wherein the alkalisoluble resin is selected from the group consisting of polycarboxylicacid homopolymers, copolymers and mixtures thereof, and rosin esters. 6.kit according to claim 1, wherein the floor finish composition comprisestwo or more acrylate polymer forming components of different molecularweights present in amounts sufficient so that the uncured compositionhas a viscosity between about 2 centipoise and about 1,500 centipoise at25° C.
 7. A kit according to claim 1, wherein the floor finishcomposition comprises about 50 wt. % to about 99.9 wt. % polymer formingcomponents and about 0.1 wt. % to about 15 wt. % photoinitiator, basedon the total weight of solids in the composition.
 8. A kit according toclaim 1, wherein the polar solvent is denser than water.
 9. A kitaccording to claim 1, wherein the polar solvent comprises benzylalcohol.
 10. A kit according to claim 1, wherein the wherein thestripper composition has a diffusion rate through the cured finishgreater than about 7×10⁻⁷ g/2/sec.
 11. A kit according to claim 1,wherein the stripper composition has a diffusion rate through the curedfinish of greater than about 1×10⁻⁶ g/2/sec.
 12. A kit according toclaim 1, wherein the stripper composition comprises about 10 wt. % toabout 40 wt. % water-soluble glycol ether, about 1 wt. % to about 40 wt.% alkali or alkanolamnine, about 1 wt. % to about 20 wt. % surfactant.13. A kit according to claim 1, wherein the stripper compositioncomprises a blend of primary solvent, first solvent/coupler and secondsolvent/coupler that together form the organic phase of a dispersionwhen combined with water, wherein the water solubility of the firstsolvent/coupler is greater than the water solubility of the secondsolvent coupler and the water solubility of the second solvent/coupleris greater than the water solubility of the primary solvent.
 14. A kitaccording to claim 13, wherein the blend comprises about 1 to about 75wt. % of a first ether alcohol solvent having a solubility in water ofless than about 5 wt. % of the solvent, and about 1 to about 75 wt. % ofa second ether alcohol solvent/coupler having a solubility in water ofabout 20 to about 100 wt. % of the solvent coupler, and wherein thevapor pressure of the blend was less than 1 mm-Hg.
 15. A kit accordingto claim 1, wherein the floor finish composition is packaged as aconcentrate intended to be mixed with water or another suitable solventat about a 15 to 40% solids level prior to use and the strippercomposition is packaged as a concentrate intended to be mixed with wateror another suitable solvent at about 5-30% by weight prior to use.